Catalyst composition



Patented Dec. 8, 1953 UNITED STATES ENT OFFICE CATALYST COMPOSITION,Donald C. .Christain and RpbertrM. Reed, Louisville, Ky., assignors,bymesne assignments, to

iNationaI Qylinder Gas Company, Chicago, 11L, a corporation of DelawareNo -Drawing. "Original application March 8, 1948, Serial No. 13,738.Divided :andthieapplication July l 21 1951,. Serial No. ..2.38,004

'5 Claims. ((1252-1470) a This, application is :a division ofcourcqpendl-ng anplicationserialjNo.113,738,filedMamhdlSiS,

vnow U. .s. Patent No. 2., 02,0 and ass gned t the same assigneeasthe,presentinvention.

This invention relates to a processiorproduc- ,ing hydrogen andcarbqndioxide "by passing a ,mixture of gases containing carbon monoxide andwater vapor overna catalystat elevated temperatures, and to an improvedcatalyst ioruse in carrying out such process. "More particularly, .theinvention 'is directed ,to an improvement 'in thecstep of initiallyincreasing the temperature .of the catalystaand-to a catalyst capable ofwithstanding the conditionsinci'dent to the initial heating withoutimpairment of it .physical or catalytic properties.

.As is well known, in'the art, the production of hydrogenand carbondioxide by, the. catalytic reactionor conversion of. carbonmonoxide andwater vapor ina mixtnrego'f gases iscarried out at elevated temperatures(.e. g., 650" F. to '1'000';F.)

in order to, accomplishtheconv s on, a commercially practicable rate. Inpracticathe mix ture of gases containing r. carbon monoxide I and steamor water .vapor enerally is preheated to substantially the desiredreaction temperature prior to being passed in contact with the catalyst.In addition, the temperature of the catalyst is commonly increasedsubstantially to the temperature at which'the reaction is'to becarriedout before the gaseous reaction mixture containing carbon. monoxideandWateryapor is brought into contact vwith the-catalyst. Because oiftheexothermic nature of the. reaction to the objection that val-great deal.of-time-andexpense is involvedi'in initially: bringing the catalystmass up to -thertemperature essential in carrying out the reaction. Thecatalysts'heretot-ore available-for use in the conversion of carbonwmonoxide and-watervaponto: hydrogentand carbon diox-i'de f'have be'encharacterized by extremely poor; resistance to liquid water mani---fested,- by .a .tendency': to disintegratesand: impede the-normalilowoizgases after being-subjected to 'moisture or 11-iquid ,water -;such :as would yresult fromt:conden tionw f:steam. i hereio e i hasbeenin ce sary sil carr @1 h sten of nitially nr heatin l h isetalv chwhe-use 0f yle es c e ibvdrqeen rni ro en t a i e ens ti nn teamp ate peinth ca al stm ln-orderito acco l s thi r heatin thud asesitzhe teiq q iha be n c s y to rovid m .oril s labor t auxili r sy ms f9 c u a ne rycli dr i e t, at d ea e through'thecatalysti mass. These auxiliarysystems, representing appreciable investment in piping, valves, heaters,and pumps, areidle during the n ma e a ion .of th p o F the e, inc heentir h ating Of th c lyst mass must beaccomplished by thesensibleheatavailable in the dry gases, the preheating operation i ece sarilyt mecen nmin o ex mpl from; 2 4 to about 48'hours' is, commonly required tobring the catalyst up to the desired reaction temperature. it -;isobvious that the excessive :time and expense involved in preheatingthecatprocess are required. I

Attempts have been made to expedite the step 1 of initially raising thetemperature :of the catalyst by employing dry=preheating gases attemperature substantially above the reaction'temperature at whichthecatalyst is intendedto be used. 'However,such-attempts have beengenerally unsuccessfulbecause of the sensitivity-to overheatingof ironoxide catalysts of the more active type, which preferablyare employed inthe conversion of carbon monoxide and water vapor to hydrogen and carbondioxide. For example, it'has: been-found that the efiectiveness'ofcatalysts of: this type is appreciably reduced after exposure totemperatures-of more than about 1000" F. "It has-also been suggestedtoincrease the esensible 'heatavailablefor heating the catalyst bypassing the 'dry --preheatinggases in contact with the catalyst mass atvelocitie substantially higherzthan the-gas velocity normally employedin the conversionprocess. However, the excessive pressure-drop andresulting increased cost O'tcirculating the drygases incident to thehigher velocities makes the use ofthis Ia-ttermeasure undesirable.

"It is,- thereforaan object of this invention to provide, inthemethodofpreparing hydrogen and :carbon dioxide =by::the catalyticreaction'ofcarbon; monoxide and :watervapor,-an improvement :in' the stepofinitially heating the catalyst beore pa s ne-ee es co aini ca bn.,monqxid and watervapor; in-contact with the catalyst.

Another object, isytheprovisionof an improved method of preparing,llydrogen andi carbon dioxide by passing ,a, mixture ,of gases containingcarbon ,monoxideand wa e a or were cata yst ateleiatee -temperat res whc in lude thest p of initially raising the temperature ofwliheflatalystby passing steam in contact with the catalyst.

A further object is the provision, for use in the production of hydrogenand carbon dioxide by the catalytic reaction or conversion of carbonmonoxide and water, of a catalyst compact capable of being heated fromordinary temperatures to temperatures above the condensation temperatureof water vapor under conditions of pressure prevailing in the system bypassing steam in contact with the catalyst, without impairment of thephysical or catalytic properties of the catalyst.

A still further object is to provide a catalyst compact of the ironoxide-chromium oxide type capable of retaining it physical and catalyticproperties in the presence of moisture such as results, for example,from the condensation of steam on the surface of the catalyst compact.

Briefly, the catalysts of our invention are produced by compressing orcompacting as, for example, by tabletting, under carefully controlledconditions, an intimate mixture of substances substantially free ofwater soluble material and consisting essentially of iron oxide,chromium oxide, a lubricant, and water.

We have discovered that when catalyst mixtures of the followingcomposition are prepared and compressed in the manner hereinafterdescribed, catalyst compacts capable of withstanding contact withmoisture without impairment of physical or catalytic properties andhaving excellent mechanical strength are obtained:

Per cent by weight Chromium oxide (calculated as CrQOs) 1-15 Water 21-28Lubricant 0.5-2.0 Iron oxide (calculated as Fezos) Balance As indicatedabove the catalyst compacts of our invention may contain from 1% tochromium oxide. However, we have found that a chromium content of about8% affords catalyst compacts having the optimum desired properties,particularly from the standpoint of conversion efiiciency when employedin the production of hydrogen and carbon dioxide by the catalyticreaction between carbon monoxide and water vapor.

In the preparation of the catalyst, an intimate mixture of chromiumoxide and iron oxide is first granulated by any of the methods wellknown in the art such as, for example, by passing the mixture through ascreen of suitable mesh size (e. g., 6 to 10 mesh). Water in amountscorresponding to approximately 13% of the catalyst mixture prior to thecompression step is present in the original mixture of oxides incombination therewith, presumably in the form of the metal hydroxides orhydrated oxides. The original mixture of oxides may contain additionalfree water in amounts sufiicient to bring the total amount of water inthe ultimate catalyst mixture up to the total desired 21% to 28%.However, the additional water is not essential in the step of originallygranulating the mixture of oxides and may be added subsequently in thepreparation of the catalyst mixture as will be pointed out in thefollowing description of our invention. It is important that theoriginal mixture of oxides be essentially free of Water solublematerials and that no water soluble materials be subsequently added inthepreparation of the catalysts of this invention in order to obtaincatalyst compacts having the desired resistance to moisture.

In order to facilitate the hereinafterdescribed compacting or tablettingoperation, a small amount of water insoluble lubricant is'added to, andthoroughly mixed with the granulated mixture of oxides. The quantity oflubricant added depends to a large extent on the properties andeffectiveness of the particular lubricant. However, in general, we havefound that from about 0.5% to about 2% of lubricant is desirable.Illustrative of materials which are capable of being uniformlydistributed throughout the granulated oxides and which are effective aslubricants in the subsequent compacting or tab letting of the catalystmixture are graphite, talc, colloidal clays, hydrocarbon oils and waxes,higher molecular weight fatty acids (e. g., stearic, palmitic, andoleic), esters of higher molecular weight fatty acids such for example,the monoand tri-glycerides of such acids, and insoluble salts of highermolecular weight fatty acids such as, for example, the zinc and calciumsalts.

In addition to the lubricant, additional water may be added to themixture to facilitate the compacting of the catalyst mixture and toprovide a catalyst compact having the desired me chanical strength.However, if the original mixture of oxides contains sufiicient freewater, the addition of more water at this point is unnecessary. We havediscovered that certain amounts of free Water, in addition to the waterchemically combined with the oxides, must be present in the granulatedmixture prior to the tabletting step to afford catalyst compact havingthe desired optimum mechanical strength. The amount of free water may beas low as about 8% out should not be greater than about 15%. If theamount of free water in the mixture exceeds 15%, catalyst compactsprepared from the mix ture tend to be fragile or lacking in thenecessary properties to resist handling and storage, and tend todisintegrate and impede the flow of gases during use. In general,catalyst compacts of optimum mechanical strength and catalyticeificiencies are obtained with mixtures containing from about 10% to 13%of free or uncombined water.

The lubricant and any additional water which might be added arethoroughly distributed throughout the granulated mixture of oxides byany suitable means well known to those skilled in the art such as, forexample, by ball milling, tumbling, or by pan mixing. In order tofacilitate handling during the tabletting operation hereinafterdescribed, and to obtain a catalyst compact of the desired mechanicalstrength and resistance to moisture, the mixture should be free flowing,and preferably a substantial proportion should be in granulated formafter the lubricant and any additional water have been thoroughlyincorporated with the oxides.

Th above described mixture of oxides, lubrlcant, and water is nextcompressed into the form of a catalyst compact by any method well knownin the art as, for example, by means of an automatic tabletting machine.Various pressures may be employed in compressing the material. However,we have found that in order to obtain the optimum mechanical strengthand resistance to moisture desired in our finished catalyst compact, thematerial should be tabletted or compressed under pressures of at leastabout 35,000 pounds per square inch. We prefer to employ pressures ofbetween 35,000 and 50,000

pounds per square inch in this operation.- If

magmas The catalyst compafzt oriin.qreiizas-i cieserribfidiahOVBIHaYCbBiJILZthQ' f i ofzpelle if; Vat sizes andishape dependail-non he eon t1 hydrogen: andx a' conversion f:; 1.1 wea-prefercataiyst:Dells. cylinderscofi pnrwimate ha.ving:.s.con;ysx; endzsurf st:compaets osh- :me-

air;as: possiblev-betfolic i catalyst: mixture; clarinet: the 1: cmpressio tabletting; operation; IeahaYe -mnn tabletting: operation ThisiI1 IZfiS%:m, tIL a. is, apparent-ly attributable the faot thats hranulanmixtureaemnloy d: inane-sec nd i l Q- ting operation contains1eseainthan waszpresentqiniztneaorigmalzsranulamcatedystam attire-s. I h

second compression operation: isaemaoyeci; maybeiiound:economical;itorcoiiipress hero tam lystzmixture intozshanesofelargerzthanzthesul mately desiredshapedurine he-first tom-pressortabletting'pperation was cfoundrto :besparticularlyg;etiectiye foruseqin; theeproduction:of:hydrogemanclsoarbonsdioxiderz. andzzwithstoodzourzimpr ved j onirersio amethoiii' intiolfil'ing-sthe sSEQlXiO 'tiallfrthee-cataan 5 st; massxswith steam to; he amerature:withoutzimpairmentrof 'the=el h.,'siea1 oracatalytioproperties:a0titheeatalystacompaot.;

One hundred fifty (150) .pounds:iof;--lumii Ina-1. terial:remainingapproximately 3% tbyzweight .of

chroniiumgoxide and ths.;ba1ance ;ir0nz;oxide:.:and;z 50 fromarravaila'bie: steam dine:

combined -waterl were; granulated; ohm-ugh 8;rr;i eshsciieencThegranulatedimixturaofioxides was henztransferred toz awmechanieaimixer of? the: pairitype inmwh-iehizth'e mixingxwas 1 8.060111%.

' Inordemto dete min the-s ii ti ene snfthe zo-rperiod of operation:.1n"i chinesatzai: PISS11I63 02.. :hq. l t:# ,,Q,09-; per meter: squareinch; In this second compression step;;,,

catalyst :peliets%iinQh iamstetand-1% lieh hiehwerezpr eiic ds '11.

above ic ta-l-ysts mn etz ancieme ho d; nitially: heatin the' ataiystjin,ppli at onsirequ r ns fre.' quent;

described ab oye:-;was emplo d; in; the iPrOduQtiQII' ofvrh ydrogenanqmao ,d QXide-ior a period of 1' 103, days. nuring thisxiodxthesprooess was;in-,

terruptfidiandragainififiti d: ups-17 times." Each: al5i'tim tne prQcesswas-sta ed, the atalyst'm ssz was initially. heated byxsmeahsmf, team- Cm.-

arison1Mather-pressuresdropsaov er the; catalyst mass and"QOIISLEEISiOiIrEfiQiBI-lflifis during he cone versihsstepzsatgthebeginning-12inch end of this cated :no observable dif-'ferences; Theephysicali'andatcatalytiomroperties fizthe cataiystipnarently remained substantially unaifiected .iby the. repeatedfiflntaot with moisture cit'ie the nerioclgindicatewnowbservabbdisintegration or change in:,mechanioal,strengtin,v

Beoausamfi :the ability: of: the; cataiystcompact OfIOilIEiILlGIHZiOIitoswithstandirequent-zand proso longestcontactewithimoistureWithoutdmpairment;

ofg-the ,physioalgandi catalyticproperties of the compacaithetemperatureiof amass: or -bednofv the oompaotvcan'zbe rapidly: raisedtfromiordinary temperaturess tosanycdesiredv elevated temperature-.1ii351 -:by passing steam through the mass without re-.v

the; mas.s;. Instaking advantage;oithistproperty of-zzourtcatalyst,wehaye foundlthat-tthe z reheat 7 ingQifcatalystiamassessemployed:imthematalytio: Amatalyst compactpreparedasdeserihedsb owi aotconversioneof-"carbon monoxidetandzwater vapor-*-into; hydrogen and carbon; dioxide;- cans be ac oompiished tin less-.1timeh a-nd \Vith far: greater economy bypassing:steamnthrough therate-13 stmass atha-nsheretefore has; been possible pre-Q onversionf:heatingzithe catalyst: bytcirculating hot; dry inert asesrthroug-h'athemassa In. -preheating.+the catalyst mass in armor-d.ance With-@0111;inventiom-steam is admitted tothe conversionv chamher,- containing. thecatalyst mass, Steam ofanypressure or any desiredidegreeof superheat mays--beiemployed;-f although it preferable thattheitemperature-ofxt-heisteambe sufficiently high I to :heat; :thecatalyst -mass substantially to the plished qby-meanSof:a::-mu11er:;whee1 ironing over.- temperature desired-rop-carryingoutthecon version ofs-carbon monoxide- (e; g., 650 F}- 10911? Ifrsteam-iof:'suifioient-1y h'igh tempei atareis not: availabiew steam oflower-temperature may be preheated; to thedesiredtemperatur.before-beingadmitted te Contact with the cat. yet-mass; At the:beg-inning cf=thisinit-i 1 heating stfiprthe temperatureoithe-catalystcom paot issbelnwithe-maximum temperature at which th'e steamcondenses-tat"thepressure the cataduring th"e m,ixing onerationqto avoidexcessive :lystifmasslflnd?appfesiablequantities Ofymqisture pulverizingofth'e material? Aftertthergranulated catalyst v mixture was, re-

moved. from the mixer it was compressed in an automatic-tab1ettingmachine at-a -pressure of aboutAMlOO pounds per squarerinch.The cont-J0 p G base-115st? the available :latentheatlin the steam;preheating pant Resulting. from, this "compression operation was; in.,the fqrn r,o-ii.cylindriealgpellets about inch:in'rdiametenandiinchshighe Thesespell'ets wereitthanemnulatediihIiOllghlfiIlf8-1'ileshi screenaoeumu1ate..-onthesurfacesot-thecatalyst come pact. moisture :preferablyis drainedfroin' the catalyst mass to avoid the accumulation ofezcessiveequantities:of "water-i Those skilled in ofrthe catalystmassiwith steam is aocomplisheci asfiiaseheretofore. been the=practioa-This-isparandgcompressedinan. automatic-1ztablettingamm ticulanlytrneatgthe bsginningiot the-initial heab .n oir hep le s we e A I teruniionzinithe ye onrersion: process: a 10 imass iDf? catalyst, elletsape ared-ias s e i l t omreheatinathe catal st: with steam-.7 5;.Insneo onofisthe-zcatalystiapeiletsat the endiofr ing step, during condensationof the steam on the catalyst compact.

The rate of heating of the catalyst may be increased as much as desiredby the simple expedient of increasing the velocity, or quantity, ofsteam passed in contact with the catalyst. It is realized, of course,that the velocity of the steam must not be increased to the point wheremechanical disturbance and damage to the catalyst mass might result.Those skilled in the art will appreciate that very little additionalcost is involved in overcoming the pressure drop over the catalyst massincident to higher rates of flow of steam obtained from a high pressuresource. On the other hand, as has previously been pointed out, theincreased pumping costs involved in overcoming this pressure drop whereheated, dry, inert gases are employed, in accordance with the methods ofthe prior art, make undesirable the use of such gases at highervelocities.

The length of time required to bring the catalyst mass up to the desiredtemperature may vary widely depending for example, on the type ofconversion chamber employed and the arrangement of the catalyst masswithin the chamber. After the catalyst mass has been brought up to thedesired reaction temperature, the heating steam passed in contact withthe catalyst is reduced at any desired rate, and a reaction gas mixturecontaining carbon monoxide and water vapor is started through thecatalyst mass. The conversion of carbon monoxide and water vapor intohydrogen and carbon dioxide then proceeds in the manner well known tothose skilled in the art.

Although the practice in the art has been to initially heat the catalystby passing heated, dry, inert gases through the catalyst mass for thespecific purpose of avoiding the condensation of moisture on thecatalyst, we have found that, by employing the particular catalystcompacts described herein, we are able to carry out the initial heatingstep by passing steam in contact with the catalyst without regard to theresulting condensation of moisture on the catalyst. Furthermore, thereis no indication of impairment of the physical or catalytic propertiesof the catalyst as is evidenced by the constant pressure drop over thecatalyst and the constant conversion efficiency determined from analysesof the reaction and product gases.

The present invention is generally applicable to the production ofhydrogen and carbon di oxide by passing a mixture of gases containingcarbon monoxide and water vapor in contact with a catalyst at elevatedtemperatures. In addition tothe carbon monoxide and water vapor, variousamounts of other gases may be present in the initial mixture of gasessuch as, for example, nitrogen, oxygen, carbon dioxide, and hydrogen,depending on the source of the gas mixture. Gases which may be subjectedto the conversion method to which this invention relates may beobtained, for example, by the well known producer gas method, the watergas method, or by the catalytic reaction of hydrocarbons and water vaporat elevated temperatures.

We claim:

1. An improved catalyst compact obtained by compressing under a pressureof at least 35,000 pounds per square inch an intimate mixture ofingredients consisting essentially of iron oxide, chromium oxide, 2.small amount of lubricant, and from about 21% to about 28% water ofwhich between about 8% and about 15% is free water.

1 compressing,

said compact being substantially free of water soluble materials andcapable 01 being heated from ordinary temperatures to elevatedtemperatures, by passing steam in contact therewith, without impairmentof the physical or catalytic properties of the compact.

2. An improved catalyst compact obtained by compressing under a pressureof at least 35,000 pounds per square inch an intimate mixture ofingredients consisting essentially of iron oxide. between 1% and 15%chromium oxide, a small amount of lubricant, and from about 21% to about28% water of which between about 8% and about 15% is free water, saidcompact being substantially free or water soluble materials and capableof being heated from ordinary tempera tures to elevated temperatures, bypassing steam in contact therewith, without impairment of the physicalor catalytic properties of the compact.

3. An improved catalyst compact obtained by compressing under a pressureof at least 35,000 pounds per square inch an intimate mixture of iningredients consisting essentially of iron oxide, from about 1% to about15% chromium oxide, from about 21% to about 28% water of which betweenabout 8% and about 15% is free water, and from about 0.5% to about 2% oflubricant, said compact being substantially free of water solublematerials and capable of being heated from ordinary temperatures toelevated temperatures, by passing steam in contact therewith, withoutimpairment of the physical or catalytic properties of the compact.

4. An improved catalyst compact obtained by compressing, at pressures ofbetween 35,000 pounds per square inch and 50,000 pounds per square inch,an intimate mixture of ingredients consisting essentially of iron oxide,from about 1% to about 15% chromium oxide, approximately 13% watercombined with said oxides, from about 10% to about 13% free water, andfrom about 0.5% to about 2% graphite, said compact being substantiallyfree of water soluble materials and capable of being heated fromordinary temperatures to temperatures between 650 F. and 1000 F., bypassing steam in contact therewith, without impairment of the physicalor catalytic properties of said compact.

5. An improved catalyst compact obtained by at pressures of between35,000 pounds per square inch and 50,000 pounds per square inch, anintimate mixture of ingredients consisting essentially of iron oxide,about 8% of chromium oxide, approximately 13% water combined with saidoxides, from about 10% to about 13% free water, and from about 0.5% toabout 2% graphite, said compact being substantially free of watersoluble materials and capable of being heated from ordinary temperaturesto temperatures between 650 F. and 1000 F., by

passing steam in contact therewith, without im pairment of the physicalor catalytic properties of said compact.

DONALD C. CHRISTAIN.

ROBERT M. REED.

References Qited in the file of this patent UNITED STATES PATENTS NumberName Date 1,908,484 Larson May 9, 1933 2,106,597 Ferguson Jan. 25, 19382,229,199 Voorhees Jan. 21, 1941 2,276,679 Abbott Mar. 17. 19422,460,811 Davies et al. Feb. 8, 1949

1. AN IMPROVED CATALYST COMPACT OBTAINED BY COMPRESSING UNDER A PRESSUREOF AT LEAST 35,000 POUNDS PER SQUARE INCH AN INTIMATE MIXTURE OFINGREDIENTS CONSISTING ESSENTIALLY OF IRON OXIDE, CHROMIUM OXIDE, ASMALL AMOUNT OF LUBRICANT, AND FROM ABOUT 21% TO ABOUT 28% WATER OFWHICH BETWEEN ABOUT 8% AND ABOUT 15% IS FREE WATER, SAID COMPACT BEINGSUBSTANTIALLY FREE OF WATER SOLUBLE MATERIALS AND CAPABLE OF BEINGHEATED FROM ORDINARY TEMPERATURES TO ELEVATED TEMPERATURES, BY PASSINGSTEAM IN CONTACT THEREWITH, WITHOUT IMPAIRMENT OF THE PHYSICAL ORCATALYTIC PROPERTIES OF THE COMPACT.